The present invention relates in general to telecommunication equipment and local area networks, and more particularly to an arrangement for extending an Ethernet network and allowing subscriber access to the internet network, without tying up voice paths in central office switching equipment.
The widespread use and advancement of telecommunication equipment and services have facilitated the dispersal of information of all types, including personal, business, governmental, educational, etc. It is not without question that there is a significant benefit to society when information of all types is readily available. While public and institutional libraries have been available for many decades for allowing access to the vast volumes of information, the access to such information was often burdensome and time consuming.
The popularity of the internet, and the access thereto in recent years, has enjoyed a great deal of success, due primarily to the ease of access and the ability to provide new and updated information and data on a daily or hourly basis. Moreover, with the abundance of home and office computers, and with the proliferation of internet service providers, access to all kinds of information can be readily had by a person at either the office or home using a computer, and at the convenience of the subscriber. A subscriber connected to the internet via a telephone line modem and service provider can browse through the various internet data bases, generally at only the cost of a connection to the internet service provider. With regard to internet subscribers, an internet connection is generally accomplished by the modem dialing a local number. The telephone operating companies thus do not obtain revenue therefrom, as such calls are often not of the toll or long distance type. The revenue obtained by the telephone operating companies for internet connections is generally only for leased lines from the internet service provider to the internet connection point. Despite that the local telephone operating companies have had to accommodate the additional load imposed on them for providing telephone connection services, very little, if any, additional revenue has been gained.
The internet architecture includes a government-installed network, termed the xe2x80x9cbackbonexe2x80x9d, to which many governmental and educational institutions are directly connected. Accordingly, a vast amount of data and information is easily distributed throughout government and educational institutions by large mainframe computer data bases, without involving private or public telephone companies. In order for individuals and businesses other than those with internet mainframe computers to be connected to the backbone, many service providers, i.e., web sites, have become available for connecting subscribers to the internet. The web sites themselves also employ additional data bases which are accessible by any person wishing to access the internet. Generally, subscribers establish internet connections by dialing via analog modems to a modem xe2x80x9cpoolxe2x80x9d that is served by a computer of the internet service provider. The web site computer then provides a connection appearance to the internet via a high speed leased line ultimately to the internet backbone. Each subscriber has a unique IP address, and each service provider has a unique address, such as mainhost.Cyberspace.net. In like manner, the address of the service provider is generally known as a domain name server. Similarly, each web site has a unique address, such as http://WWW.UH.edu. As noted above, while the local telephone operating companies do not obtain additional revenues from the subscribers during the connection to the internet, certain revenues are obtained for the high speed leased lines.
With the widespread use of the internet by many individuals using analog modems, substantial traffic burdens have been placed on the public telephone network, in that the local telephone operating company provides a switched network connection for each subscriber to reach the service provider. While such internet connections at the local central office do not involve any technical problems, such connections do indeed reduce the capability of the telephone companies to handle the routine telephone set traffic, especially during peak demand periods. It is well known that the traffic needs of telephone switching equipment are based on the statistical average of routine telephone calls. In practice, an average telephone-to-telephone call lasts approximately 100 seconds. Thus, based on the plain old telephone service (POTS), even at peak demand periods when the switching network may be operating at full capacity, a user does not need to wait for a very long period of time in order to complete a connection through the network to a destination, whether it be local or long distance. However, the telephone network connection provided for an internet subscriber lasts significantly longer than the nominal 100 seconds, and may remain for hours.
A central office connection provided by a local telephone company that is dedicated to a single subscriber for many hours thereby disrupts the statistical traffic demands that are normal for routine telephone calls. While the telephone operating companies can overcome this problem by expanding the central office switching equipment to accommodate more subscriber connections, such solution involves extremely costly equipment, space and time to install new switching equipment.
The information provided to internet subscribers often involves video data in the nature of graphics. In order to recreate pictures or graphical data on a CRT via a standard 28.8K analog modem, a substantial amount of time is incurred in waiting for the transfer of large amounts of video data, as well as the display of the same on the CRT. This waiting period is due primarily to the bandwidth bottle-neck of the modems. While ISDN data links are available, and operate between 56 and 128 kilobits per second, the use thereof does not significantly overcome the waiting problem.
The bandwidth problem can be overcome by the use of optical fibers that are higher speed and more environmentally durable than the traditional twisted copper pairs. However, the installation of fiber optic transmission facilities is costly, and thus acceptance thereof has been generally limited to high traffic situations. There is, however, a continued growth of the use of fiber optic telecommunications into residential neighborhoods. An emerging technology in this area is called xe2x80x9cfiber to the curb.xe2x80x9d RELTEC Corporation of Bedford, Tex. is a leader in providing this new technology. Even with fiber optic capability extended to residential homes, apartments and businesses, the primary usage thereof is yet for routine telephone calls and computer modem traffic. As such, the fiber optic systems represents excess capabilities that are not used to the fullest extent.
It would be highly advantageous to utilize the high speed optical medium for computer network capabilities, especially in view that many residential homes and/or offices are equipped with computers and modems for accessing the internet as well as a host of other services. The networking of computers is a well-established function that allows a number of computers to communicate with each other according to a predefined protocol. One of the most popular network protocols is the Ethernet protocol, or otherwise known as the IEEE 802.3 standard. While this local area network protocol functions ideally in a local area, it is not easily expanded geographically without the use of expensive xe2x80x9cnetworkxe2x80x9d bridges. The area limitations of the Ethernet protocol is based primarily on the xe2x80x9cround trip timingxe2x80x9d of signals carried on the network. This period of time is directly related to the physical length of the network medium and the time delay of electrical signals carried by the medium. According to the Ethernet standards, in order to minimize signal attenuation, each source or destination computer must be no further from the network than about 328 feet. The Ethernet protocol includes an algorithm to detect when two computers attempt to transmit data packets on the network at the same time and avoid the corresponding xe2x80x9ccollisionxe2x80x9d of signals. To date, there has been no acceptable solution for extending the geographical area of an Ethernet network without utilizing expensive bridges. While the use of bridges is widely known, such solution involves the receipt of the data packets, decoding the various fields and otherwise processing of the data fields themselves, and the attendant slowing down the transport speed of the overall data transmission.
From the foregoing, it can be seen that a need exists for a technique to provide users with connections to the internet, without tying up local central office switching equipment for long periods of time. A further need exists for the use of conventional equipment and software to provide such connections to internet services, without the need for new or expensive computer equipment or software protocols. Another need exists for a better utilization of fiber optic and other high speed data transmission facilities that are available to residential users. A significant need exists for extending data networks without the use of bridges and similar equipment while yet maintaining conformance to the appropriate protocol. Another need exists for providing an improved utilization of high speed data lines in extended data networks, and providing residential and other users further incentives to use high speed data services.
In accordance with the principles and concepts of the invention, disclosed is a technique for overcoming or substantially reducing the problems attendant with the traditional connections provided to the internet, via the local telephone operating companies.
In accordance with an important aspect of the invention, rather than employing modem data coupled through the switching fabric of a central office, the subscriber""s personal computer employs a conventional network card to generate data packets according to a standard local area network protocol, such as Ethernet. The data packets are thereafter multiplexed with other data packets and converted to corresponding optical signals for transfer via an optical fiber medium to an Ethernet switch or other similar equipment, such as a LAN adapter located in the central office. The central office allows the internet connection request to be switched and/or transferred external to the switching fabric via high speed lines for subsequent connection to the internet backbone. With this arrangement, unlike the traditional modem data, the data packets communicated between the internet and the subscriber personal computer are not carried or switched through the switching fabric of the central office. Thus, lengthy internet connection periods do not adversely affect the voice traffic carrying capability of the central office switching system. Also, by reason of the central office capability of processing internet access requests, the central office can itself function as a service provider, i.e., as a domain name server.
In the preferred embodiments employing the invention, a household or office personal computer is connected to a standard twisted pair having a 10 MHz bandwidth for carrying Ethernet data packets or frames. The data packets are transmitted on the twisted pair at a 10 MHz rate by a 10-Base-T transmission method. Within no more than about 500 feet of home or office personal computers, there is located an optical network unit for converting the digital signals of the Ethernet frames to corresponding optical signals that are carried on a fiber optic line. The optical network unit provides a carrier sense multiple access with collision detection (CSMA/CD) functions with respect to the computer connected to the 10-Base-T input ports thereof. In addition, the optical network unit can include additional ports to convert analog voice signals from telephone sets to PCM signals which are multiplexed with the computer digital data. Other digital carrier capabilities, such as DS1, can also be multiplexed onto the optical medium by the optical network unit. With regard to the data frames transmitted to the optical network unit by the computer, if no collision of signals is detected, then the data packets are stored in a buffer memory and retransmitted back to the other computers locally connected to the 10-Base-T ports of the optical network unit. Moreover, if no collision is detected, the data frame is transmitted as optical signals toward a central office via a host digital terminal. Importantly, a host digital terminal can be located several miles or more from an optical network unit, and can receive optical inputs from a number of such units.
The host digital terminal may typically be located remotely with respect to the central office and coupled thereto by yet other optical fiber or electrical data transmission lines. Much like the optical network units, the host digital terminal includes plural optical interface units that receive the network data frames and provide a collision avoidance function. As such, the network connection is extended from the residences beyond the traditional geographical limits, to the host digital terminal.
Each optical interface unit of the host digital terminal is interconnected by a common high speed electrical bus to provide networking of data frames therebetween so that such frames can be transmitted back to all of the other computers connected in a wide area network. In addition to the echoing of the data frames to the sources, and if no collision is detected, the data frame is read from a buffer memory and transmitted to a standard Ethernet switch where such data is transferred on a high speed line toward the internet backbone. The host digital terminal also transfers the multiplexed optical signals of PCM and DS1 data by way of fiber optic cables or electrical lines to the central office where the signals are reconverted to bipolar signals. The PCM data is switched by the switching fabric of the central office to a destination in a conventional manner.
In various other alternatives in the practice of the invention, there may be intermediate conversions and reconversions of optical signals to 10-Base-T signals before arriving at the central office. In addition, various multiplexing and de-multiplexing of the optical signals can be carried out to increase the efficiency and throughput of the system.
In accordance with another feature of the invention, the host digital terminal is adapted for separating digitized PCM voice signals originating from the subscriber""s telephone sets, from the data packets generated by the subscriber""s personal computer, whereby the digitized voice signals are routed to the central office for switching via the switch fabric, and the data packets bypass the switching fabric and are routed to the internet bridge.
In accordance with yet another feature of the invention, the data packets generated by the subscriber""s computer are preferably those that comply with the Ethernet protocol. In this manner, standard commercial personal computer software and hardware can be utilized to transmit and receive the Ethernet data packets at a 10 MHz rate, without employing any new personal computer software or hardware. By carrying out the internet bidirectional communications via Ethernet data packets, the response time to the subscriber in receiving large masses of internet information, such as multimedia information, is substantially facilitated, as compared to the traditional 28.8K data rate of a personal computer modem.